On Yosemite GM 3 or Public Beta 6 and wondering how to update to final release?

If you're already running OS X Yosemite gold master release candidate 3 (GM 3) or public beta 6 (PB 6), you won't need to update to the final release version in the Mac App Store (MAS). While there are minor differences in build numbers between the versions, Apple is considering both GM 3 and PB 6 as "final" and not offering the MAS version to anyone with either of them already installed.